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Names of rows in the Periodic Table (periods) and columns (groups) Names of the 4 main groups Names of the 3 general types of elements (metals, nonmetals, metalloids) SI units: Lab equipment The Science of Change 1 Names and symbols of elements: Numbers 1 – 38, Cs, Ba, Hg, Ag, Au, Sn, Pb Zn2+, Cd2+, Ag1+ Phases of elements ◦ Gases: He, Ne, Ar, Kr, Xe, Rn, F2, Cl2, O2, N2 ◦ Liquids: Br2, Hg ◦ Solids: All other elements A graduated cylinder is filled with water to a volume of 20.1 mL. A solid object is carefully slid into the water, and the water rises to a volume of 27.8 mL. What is the volume of the object? Temperature ◦ ◦ ◦ ◦ K, oC, oF K = oC + 273.15 F = (9/5 * oC) + 32oF C = 5/9 * (oF – 32) Worked Ex. 1.1 Problems 1.7, 1.8 Volume ◦ mL = cm3, L = dm3 1 States of Matter Metric prefixes: 10 What is happening below? Is this a physical or chemical change? What’s the difference between the two? Boiling water: physical or chemical? Lighting a hydrogen balloon: physical or chemical? Do the following equations represent a physical or a chemical change? How can you tell? H2O(s) H2O(l) CH3OH(l) + O2(g) CO2(g) + H2O(g) NH4Cl(s) NH4Cl(g) C4H10(l) C4H10(g) AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq) 11 2 Use scientific notation to describe very large or very small numbers. Negative exponents indicate small number, positive exponents indicate large number. Write the following numbers in scientific notation and place in order of increasing value: 10, 0.001, 0.00002, 1 x 104, 1 x 10-3, 3 x 10-5, 8 x 105, 700000 How can we describe the size of an atom? The size of the universe? ◦ Scientific notation and powers of ten Powers of Ten 14 Add, multiply, and divide 3.0 x 103 and 2.0 x 102 Add Multiply ◦ 3.0 x 103 + 2.0 x 102 103 To enter 3.0 x in your calculator, DO NOT enter “x” or “10”. Instead, use the exponent key (“EXP” or “ EE”). Press: 3 “EXP” (or “EE”) 3 ◦ (3 x 103) x (2 x 102) = (3 * 2) x (103 * 102) ◦ Add exponents Divide ◦ (3.0 x 103) ÷ (2.0 x 102) = (3.0 / 2.0) * (103/102) = ◦ Subtract exponents (top – bottom) Adding and subtracting exponents is a good way to estimate answers to problems!! 16 Addition and Subtraction ◦ Combine numbers with same exponent and add numbers ◦ 7.4 x 103 + 2.1 x 103 = 9.5 x 103 What is the difference between precision and accuracy? What is shown in each picture below? Multiplication ◦ Add exponents and multiply numbers ◦ 8.0 x 104 * 5.0 x 102 = 40 x 106 = 4.0 x 107 Division ◦ Subtract exponents and divide numbers ◦ 6.9 x 107 / 3.0 x 10-5 = 6.9/3.0 x 107-(-5) = 2.3 x 1012 18 3 The true temperature outside is 71.2 oF. Several thermometers made by one manufacturer record the temperature as 67.8, 68.2, 67.2, 67.6, and 68.0oF. How would you describe this data in terms of accuracy and precision? Why? What is the length of the black line in each picture (rulers shown in cm)? What are significant figures? Why are they important? http://webphysics.iupui.edu/webscience/courses/chem101/chem101/images/ruler.10.gif Measurements versus calculations: ◦ In lab, sig figs are determined by the measuring device. ◦ When measuring volume, you can always estimate 1 decimal place past the smallest increment. ◦ In class, sig figs are determined by given numbers. ◦ Sig figs for calculations are determined by the numbers reported. ◦ There are rules for determining sig figs based on calculations. How many significant figures are in the following? 1.45 0.38 0.0670 301.9 072.8 1.0 44.20 278 1098.40 0.00041560 98.76 100 190 1.90 x 103 1063 Hint: Write numbers in scientific notation to help determine if leading zeros are significant. 20 All non-zero digits are significant (335 cm). Zeroes in the middle of a number are significant (3406 mg). Zeroes at the beginning of a number are NOT significant (0.000345 km). Zeroes at the end of a number and after the decimal point are significant (43.21000 g). Zeroes at the end of a number and before the decimal point may or may not be significant (5280 ft). You will have to look at the measurement to determine this. Don’t round for sig. figs. until the END of all calculations. Multiplication and division: report to the least number of significant figures. ◦ Ex: 2.8 x 4.5039 2 sig. figs. in answer = 12.61092 13 Addition and subtraction: report to the least number of decimal places. ◦ Ex: 2.097 – 0.12 2 digits after decimal = 1.977 1.98 24 25 4 Calculate the following: 1.67890 x 56.32 ◦ 94.56 ◦ Greater mass (same vol.) = more dense ◦ Greater volume (same mass) = less dense 9.0210 + 856.1 ◦ 865.1 (6.02 + 1.5) x (3.14 + 2.579) ◦ 43 or 4.3 x 101 D=m/v Mass per volume Carbon dioxide gas is more dense than helium gas. Use the pictures below to explain why. Diet versus regular coke If a steel ball bearing weighs 54.2 grams and has a volume of 6.94 cm3, what is its density? If a steel beam is measured to have a volume of 94390 cm3, how much does it weigh? A piece of glassware is filled with water to a volume of 15.6 mL. The water is then weighed on an analytical balance and determined to have a mass of 15.2662 g. What is the density of water? Using your answer from above, calculate the volume a 56.7834 g sample of water should occupy. 28 Allows us to convert from one unit to another 1 dozen eggs = 12 eggs How many inches are in 1.3 feet? How many cm are in 12.34 in.? How many mL are in 1.450 L? How many g are in 1907.12 mg? How many mm are in 1.903 x 1010 m? ◦ 31.34 cm ◦ 1.450 x 103 mL 1 inch = 2.54 cm 3 feet = 1 yard ◦ 16 in. 1 dozen 1 12 eggs 29 ◦ 1.90712 g 1 inch 1 2.54 cm ◦ 1.903 x 1013 mm 3 feet 1 1 yard 30 5 A piece of string measures 5.5 feet long. How long is the string in mm? ◦ What conversion factors will you need to use? ◦ Plan the order of unit conversions first. A room measures 128 yd2. What is this in ft2? If you are traveling 45 mph, how fast is this in km/sec? Problem 1.17: Gemstones are weighed in carats, with 1 carat = 200 mg (exactly). What is the mass, in grams, of the Hope Diamond, the world’s largest blue diamond at 44.4 carats? The density of a steel ball bearing is 7.81 g/cm3. If the ball bearing is measured to have a volume of 1.34 cm3, what is its mass in milligrams? 32 Dimensional Analysis: One lap in an olympic swimming pool is 50 meters exactly (2 sig figs). If an athlete swims 81 laps in one practice, how far did he/she swim (in miles)? 1 inch = 2.54 cm (exactly) 12 inches = 1 foot (exactly) 1 mile = 5280 feet (exactly) 6